Conventional medical procedures involving guidewire introduction, insertion and manipulation are well known. For example, a conventional method for angioplasty generally includes the steps of inserting a guidewire through an angiographic needle into the femoral artery, and digitally manipulating the external proximal end of the guidewire to advance the distal end of the guidewire through the patient's arterial tree, to the proximal aorta. A conventional percutaneous catheter, which generally has a much larger diameter than the guidewire, may then be easily and rapidly fed coaxially over the guidewire directly into the vasculature to perform an appropriate diagnostic or therapeutic procedure. Other medical procedures use similar guidewire introducing techniques for subsequently introducing, removing, or exchanging various catheters and like apparatus.
Insertion and manipulation of a guidewire in such procedures may be difficult and time consuming. Initially, guidewires have small diameters (e.g., 0.018 to 0.030 inch) and are extremely flexible. Thus, guidewires have a drawback in that they may bend and kink during insertion and manipulation. The incidence of kinking increases in procedures where the guidewire must be maneuvered through a diseased (sclerotic) portion of an artery, which may be hardened and include various obstructions, such as plaque.
Conventional guidewires typically are provided with a soft "J-tip". Specifically, the distal tip of the guidewire is made extremely flexible and is curved back upon itself to form a "J". This design has two advantages. First, it prevents punctures, e.g., piercing of the artery wall, by the sharp pointed guidewire during advancement. Second, the soft flexible distal end facilitates advancement in a snake-like movement. More particularly, advancement is achieved by a repeated combination of axial movement and torsional twisting generated at the externally exposed proximal end, to guide the soft flexible distal end through the arterial tree.
Such "J-tips" also have drawbacks. In particular, it is difficult for the clinician to insert the soft, flexible, curved distal tip into a small diameter guiding catheter, e.g., an angiographic needle.
Conventional guidewires also generally are provided with a protective coating, such as tetrafluoroethylene (Teflon.TM.) or the like, which prevents blood from clotting on the guidewire and is biocompatible. However, such coatings have a drawback in that the coated guidewire becomes more slippery when wetted, particularly with blood. Thus, it is extremely difficult to accurately and precisely handle and manipulate (e.g., pinch and torque) these small diameter guidewires with the fingers. Such digital manipulation further is complicated when the clinician is required to wear latex gloves or the like, in order to maintain a sterile operating environment.